desc: hard clipper

slider1:0<0,150,1>boost (dB)
slider2:0<-150,0,1>clip level (dB)

@slider
boost = 10^(slider1/20);
clip = 10^(slider2/20);

@sample

spl0 = sign(spl0) * min( clip, abs(spl0) * boost );

spl1 = sign(spl1) * min( clip, abs(spl1) * boost );